1. Field of the Disclosure
The disclosure relates to a coating composition and a method for forming a fine contact of a semiconductor device using the same.
2. Description of the Related Technology
In order to overcome the resolution limit of exposures in forming a fine contact of a semiconductor device, a phase shift mask is typically used or a contact is heated at above the glass transition temperature of the photoresist to cause flow (known as a resist flow process, as described in U.S. Pat. No. 6,824,951, the disclosure of which is incorporated herein by reference). Otherwise, a RELACS (Resolution Enhancement Lithography Assisted by Chemical Shrink process, as described in “Resists Join the Sub-λ Revolution”, Semiconductor International, 1999. 9, Laura J. Peters ed., the disclosure of which is incorporated herein by reference,) process is performed to reduce the size of the contact, thereby obtaining a fine contact suitable for a high degree of integration of semiconductor devices.
However, when the phase shift mask is used, a side-lobe is generated or the resolution is degraded during the process for forming a pattern.
In the resist flow process, even when the same thermal energy is transmitted to the entire surface of the photoresist at over the glass transition temperature, the flowing amount of the photoresist is larger in the lower portion than in the upper or middle portion so as to cause an over-flow, with the space between the upper portion of the patterns is wider than the space between the lower portion of the patterns.
In the RELACS process, materials are expensive, and water-soluble polymers are not completely removed but remain on the pattern to affect subsequent etching processes. As a result, it is possible to generate defects in manufactured devices, thereby decreasing yield and reliability of devices.
Moreover, when a coating process is performed on the contact, the size of the formed contact can be smaller than the original one of the contact. However, since water is used as a solvent, coating properties may be degraded.
Although an organic solvent can be used to improve the coating properties, the organic solvent dissolves a lower photoresist layer. In order to prevent the lower photoresist layer from being dissolved by the organic solvent, the coating composition should be cross-linked after the contact is formed. For this cross-linking, an additional process such as electronic beam curing, thermal curing, or ultraviolet curing is required.